fix: instructions save

Author: LuciNyan

codex-cli/src/utils/config.ts

@@ -151,6 +151,7 @@ export const PRETTY_PRINT = Boolean(process.env["PRETTY_PRINT"] || "");
 export const PROJECT_DOC_MAX_BYTES = 32 * 1024; // 32 kB
 
 const PROJECT_DOC_FILENAMES = ["codex.md", ".codex.md", "CODEX.md"];
+const PROJECT_DOC_SEPARATOR = "\n\n--- project-doc ---\n\n";
 
 export function discoverProjectDocPath(startDir: string): string | null {
   const cwd = resolvePath(startDir);
@@ -305,7 +306,7 @@ export const loadConfig = (
 
   const combinedInstructions = [userInstructions, projectDoc]
     .filter((s) => s && s.trim() !== "")
-    .join("\n\n--- project-doc ---\n\n");
+    .join(PROJECT_DOC_SEPARATOR);
 
   // Treat empty string ("" or whitespace) as absence so we can fall back to
   // the latest DEFAULT_MODEL.
@@ -456,5 +457,10 @@ export const saveConfig = (
     writeFileSync(targetPath, JSON.stringify(configToSave, null, 2), "utf-8");
   }
 
-  writeFileSync(instructionsPath, config.instructions, "utf-8");
+  if (config.instructions.includes(PROJECT_DOC_SEPARATOR)) {
+    const userInstructions = config.instructions.split(PROJECT_DOC_SEPARATOR)[0];
+    if (userInstructions !== undefined) {
+      writeFileSync(instructionsPath, userInstructions, "utf-8");
+    }
+  }
 };